Degradable cellulose acetate tow band comprising a filler

ABSTRACT

Disclosed herein is a tow band comprising cellulose acetate and a filler. The filler may be selected to have a degradation rate greater than that of the cellulose acetate. The tow band may be bloomed and formed into a filter rod, which may then be incorporated into a cigarette filter. The tow, tow band, and filter structures described herein degrade more rapidly than other known tow, tow bands, and filter structures.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No. 63/116,613, filed on Nov. 20, 2020, the entire contents and disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to tow, tow bands, and cigarette filters comprising cellulose acetate and a filler. In particular, the present invention relates to including a filler in tow, in a tow band, and in a filter, wherein the filler is selected to increase the sustainability and biodegradability of the filter.

BACKGROUND OF THE INVENTION

Cellulose esters are widely used for many purposes, including as cellulose acetate tow in cigarette filters. Although cellulose esters such as cellulose acetate are biopolymers known to degrade, the rate of degradation is slower than natural cellulose. For example, cigarette filters may take up to 15 years to degrade because cellulose acetate does not degrade until sufficient acetyl groups have been removed, allowing for microorganisms to recognize the material for degradation. After smoking, the filters are often discarded in the environment and are one of the most common forms of man-made litter in the world. An estimated 4.5 trillion cigarette filters become litter each year. Due to the degradation time of cellulose acetate and to the plasticizer contained in the filter, the litter remains longer than desirable. Although attempts have been made to form biodegradable filters comprising cellulose acetate, these attempts have been unsuccessful for a variety of reasons, including an undesirable change to the taste of the cigarette due to modifications and/or additives and degradation time not being sufficiently reduced. Molded articles made of cellulose esters suffer from similar deficiencies.

U.S. Pat. No. 5,084,296, incorporated herein by reference, discloses a composition comprises a cellulose acetate or other cellulose ester, and an anatase-type titanium oxide having (1) a specific surface area of not less than 30 m² /g, (2) a primary particle size of 0.001 to 0.07 μm, or (3) a specific surface area of not less than 30 m² /g and a primary particle size of 0.001 to 0.07 μm. For improving the photodegradability and the dispersibility, the surface of the titanium oxide may be treated with a phosphoric acid salt or other phosphorus compound, a polyhydric alcohol, an amino acid or others. Use of a low-substituted cellulose ester with an average substitution degree not exceeding 2.15 insures high biodegradability. The composition may further contain a plasticizer and/or an aliphatic polyester, a biodegradation accelerator (e.g. organic acids or esters thereof). The degradable cellulose ester composition is highly photodegradable and moldable and hence useful for the manufacture of various articles.

U.S. Pat. No. 8,397,733, incorporated herein by reference, discloses a degradable cigarette filter which includes a filter element of a bloomed cellulose acetate tow and a plug wrap surrounding the filter element, and a pill dispersed in the tow. The pill includes a material adapted to catalyze hydrolysis of the cellulose acetate tow that is encapsulated with an inner layer of a water soluble or water permeable material and an outer layer of a cellulose acetate having a D.S. in the range of 2.0-2.6.

US Patent Publication No. 2009/0151738, incorporated herein by reference, discloses a degradable cigarette filter that includes a filter element of a bloomed cellulose acetate tow, a plug wrap surrounding the filter element, and either a coating or a pill in contact with the tow. The coating and/or pill may be composed of a material adapted to catalyze hydrolysis of the cellulose acetate tow and a water-soluble matrix material. The material may be an acid, an acid salt, a base, and/or a bacterium adapted to generate an acid. The coating may be applied to the tow, the plug wrap, or both. The pill may be placed in the filter element. When water contacts the water-soluble matrix material, the material adapted to catalyze hydrolysis is released and catalyzes the hydrolysis, and subsequent degradation, of the cellulose acetate tow. The foregoing is also applicable to articles made of cellulose esters.

Accordingly, there is a need for the controlled and sustained release of a material that will aid the degradation of cellulose esters used in cigarette filters.

SUMMARY OF THE INVENTION

In some aspects, the present disclosure is directed to a cellulose acetate tow band, the tow band comprising: a) cellulose acetate having a degree of substitution (DS) of greater than 1.3; and b) a filler; wherein the filler has a greater rate of degradation than the cellulose acetate. In some aspects, the filler may comprise a monosaccharide, polysaccharide, polysaccharide ester, hydrolyzed polysaccharide, oligosaccharide, or combinations thereof. In some aspects, the filler may comprises dextran, a hydrolyzed starch, a modified hydrolyzed starch, hemp, cellulose, or combinations thereof. The filler may be present from 0.1 to 99.9% by weight, based on the total weight of the tow band, from 0.1 to 75% by weight, based on the total weight of the tow band, from 0.1 to 50% by weight, based on the total weight of the tow band, or from 0.1 to 25% by weight, based on the total weight of the tow band. The degradation rate of the filler may be at least 3% greater than that of the cellulose acetate, at least 10% greater than that of the cellulose acetate, or at least 15% greater than that of the cellulose acetate. The tow band may comprise a weight ratio of the cellulose acetate to the filler from 1:99 to 99:1, from 1:50 to 50:1, or from 1:25 to 25:1. The tow band may comprise cellulose acetate is an amount from 0.1 to 99.9% by weight, based on the total weight of the tow band. The cellulose acetate may have a degree of substitution from 1.3 to 2.9 or from 2 to 2.9. The tow band may comprise from 0.01 to 25% by weight additives, based on the total weight of the tow band.

In some embodiments, the present disclosure is directed to a cigarette filter comprising: a filter element comprising bloomed tow, wherein the bloomed tow comprises a tow band. The tow band may comprise: a) cellulose acetate having a degree of substitution (DS) of greater than 1.3; and b) a filler; wherein the filler has a greater rate of degradation than the cellulose acetate. In some aspects, the filler may comprise a monosaccharide, polysaccharide, polysaccharide ester, hydrolyzed polysaccharide, oligosaccharide, or combinations thereof. In some aspects, the filler may comprises dextran, a hydrolyzed starch, a modified hydrolyzed starch, hemp, cellulose, or combinations thereof. The filler may be present from 0.1 to 99.9% by weight, based on the total weight of the tow band, from 0.1 to 75% by weight, based on the total weight of the tow band, from 0.1 to 50% by weight, based on the total weight of the tow band, or from 0.1 to 25% by weight, based on the total weight of the tow band. The degradation rate of the filler may be at least 3% greater than that of the cellulose acetate, at least 10% greater than that of the cellulose acetate, or at least 15% greater than that of the cellulose acetate. The tow band may comprise a weight ratio of the cellulose acetate to the filler from 1:99 to 99:1, from 1:50 to 50:1, or from 1:25 to 25:1. The tow band may comprise cellulose acetate is an amount from 0.1 to 99.9% by weight, based on the total weight of the tow band. The cellulose acetate may have a degree of substitution from 1.3 to 2.9 or from 2 to 2.9. The tow band may comprise from 0.01 to 25% by weight additives, based on the total weight of the tow band.

In some embodiments, the present disclosure is directed to a method for forming a cigarette filter, the method comprising: a) providing a cellulose acetate tow band comprising cellulose acetate and a filler; b) blooming the tow band; and c) forming the bloomed tow band into a filter rod. In some aspects, the tow band is formed by: a) combining cellulose acetate and the filler with a solvent to form a dope; b) solvent-spinning the dope to form a plurality of tow filaments; and c) combining the plurality of tow filaments to form the tow band. In some aspects, the tow band is formed by: a) combining cellulose acetate and the filler to form a flake; b) combining the flake with a solvent to form a dope; c) solvent-spinning the dope to form a plurality of tow filaments; and d) combining the plurality of tow filaments to form the tow band. The tow band may comprise: a) cellulose acetate having a degree of substitution (DS) of greater than 1.3; and b) a filler; wherein the filler has a greater rate of degradation than the cellulose acetate. In some aspects, the filler may comprise a monosaccharide, polysaccharide, polysaccharide ester, hydrolyzed polysaccharide, oligosaccharide, or combinations thereof. In some aspects, the filler may comprises dextran, a hydrolyzed starch, a modified hydrolyzed starch, hemp, cellulose, or combinations thereof. The filler may be present from 0.1 to 99.9% by weight, based on the total weight of the tow band, from 0.1 to 75% by weight, based on the total weight of the tow band, from 0.1 to 50% by weight, based on the total weight of the tow band, or from 0.1 to 25% by weight, based on the total weight of the tow band. The degradation rate of the filler may be at least 3% greater than that of the cellulose acetate, at least 10% greater than that of the cellulose acetate, or at least 15% greater than that of the cellulose acetate. The tow band may comprise a weight ratio of the cellulose acetate to the filler from 1:99 to 99:1, from 1:50 to 50:1, or from 1:25 to 25:1. The tow band may comprise cellulose acetate is an amount from 0.1 to 99.9% by weight, based on the total weight of the tow band. The cellulose acetate may have a degree of substitution from 1.3 to 2.9 or from 2 to 2.9. The tow band may comprise from 0.01 to 25% by weight additives, based on the total weight of the tow band.

DETAILED DESCRIPTION OF THE INVENTION Introduction

The present disclosure is directed to forming tow, tow bands, and cigarette filters using the comprising the combination of a cellulose ester (e.g., cellulose acetate) and a filler. The cellulose ester may have a degree of substitution of greater than 1.3 and the filler may be selected to have a greater rate of degradation than the cellulose ester. In some aspects, the filler may be a monosaccharide, polysaccharide, or combinations thereof. In further aspects, the filler may comprise dextran, a hydrolyzed starch, a modified hydrolyzed starch, cellulose, or combinations thereof. The filler may be present from 0.1 to 99.9% by weight of the tow, depending on the desired degradation, filler, and mechanism for degradation. In some aspects, the filler is present from 0.1 to 75% by weight of the tow, e.g., from 0.1 to 50% by weight, from 0.1 to 20% by weight, and all values in between. The degradation rate of the filler may be at least 3% greater than that of the cellulose acetate, e.g., at least 5% greater, at least 7% greater, at least 10% greater, at least 15% greater, or at least 20% greater.

The present disclosure is also directed to methods of forming the tow, tow bands, and cigarette filters. In some aspects, the filler may be combined with the cellulose ester (e.g., cellulose acetate) to form a dope, which is then solvent-spun to form the tow. Depending on the filler, the filler may be added after the dope is formed, such as during fiber formation. Once the fibers are formed (tow), the fibers are combined to form a tow band. The tow band may then be subjected to additional treatments, packaged, and eventually formed into filter rods for use in cigarette filters.

The basic mechanism of cellulose ester degradation is dependent on the degree of substitution (“DS”) of the cellulose ester. DS of cellulose ester refers to the degree of substitution and may be measured, for example for cellulose acetate, by ASTM 871-96 (2010). When the cellulose acetate has a DS of greater than 1.3, cellulose acetate is not degraded by naturally occurring enzymes or bacteria due to the acetate moieties present. To replace the acetate moieties with hydroxyl moieties, and thereby reduce the DS, the cellulose acetate is hydrolyzed. Hydrolysis of the acetyl moieties is also referred to as deacetylation. The degradable cigarette filters described herein typically have a DS of greater than 1.3, often in the range of 2.0 to 2.6,but up to as high as 2.9 and accordingly, are not degraded by naturally occurring enzymes or bacteria due to the acetate moieties present.

Without being bound by theory, it is believed that by incorporating a filler having a greater degradation rate than that of the cellulose ester, the degradation of the tow, tow band, and cigarette filter may be accelerated. The selection of the filler is made to balance the improvements in degradation with the filtration performance. For example, the filler may be selected to have a small enough domain to avoid being filtered out. Some fillers, such as starch, glucose, or dextran, as described further herein, may serve as a food source for a variety of microbials. Such fillers would allow for the microbial growth to be established directly on the tow, tow band, or cigarette filter, leading to accelerated degradation. Combinations of different fillers may be used to take advantage of different properties and performance of the filers. For example, dextran may be included to improve degradation while hemp or short continuous fibers may be included to improve other mechanical properties.

Cellulose Ester

As described herein, the present disclosure relates to tow, tow bands, and cigarette filters including a filler, along with a cellulose ester, e.g., cellulose acetate. The filler is included with the cellulose ester, preferably prior to tow formation, in order to enhance the degradation rate of the cellulose ester. Cellulose acetate, as used herein, refers to cellulose diacetate, though the filler and methods described herein may be used for other types of cellulose esters, including cellulose triacetate, cellulose propionate, cellulose acetate-propionate, cellulose butyrate, cellulose acetate-butyrate, cellulose propionate-butyrate, cellulose nitrate, cellulose sulfate, cellulose phthalate and combinations thereof.

Cellulose esters may be prepared by known processes, including those disclosed in U.S. Pat. No. 2,740,775 and in U.S. Publication No. 2013/0096297, the entireties of which are incorporated herein by reference. Typically, acetylated cellulose is prepared by reacting cellulose with an acetylating agent in the presence of a suitable acidic catalyst and then de-esterifying.

The cellulose may be sourced from a variety of materials, including cotton linters, a softwood or from a hardwood. Softwood is a generic term typically used in reference to wood from conifers (i.e., needle-bearing trees from the order Pinales). Softwood-producing trees include pine, spruce, cedar, fir, larch, douglas-fir, hemlock, cypress, redwood and yew. Conversely, the term hardwood is typically used in reference to wood from broad-leaved or angiosperm trees. The terms “softwood” and “hardwood” do not necessarily describe the actual hardness of the wood. While, on average, hardwood is of higher density and hardness than softwood, there is considerable variation in actual wood hardness in both groups, and some softwood trees can actually produce wood that is harder than wood from hardwood trees. One feature separating hardwoods from softwoods is the presence of pores, or vessels, in hardwood trees, which are absent in softwood trees. On a microscopic level, softwood contains two types of cells, longitudinal wood fibers (or tracheids) and transverse ray cells. In softwood, water transport within the tree is via the tracheids rather than the pores of hardwoods. In some aspects, a hardwood cellulose is preferred for acetylating.

Acylating agents can include both carboxylic acid anhydrides (or simply anhydrides) and carboxylic acid halides, particularly carboxylic acid chlorides (or simply acid chlorides). Suitable acid chlorides can include, for example, acetyl chloride, propionyl chloride, butyryl chloride, benzoyl chloride and like acid chlorides. Suitable anhydrides can include, for example, acetic anhydride, propionic anhydride, butyric anhydride, benzoic anhydride and like anhydrides. Mixtures of these anhydrides or other acylating agents can also be used in order to introduce differing acyl groups to the cellulose. Mixed anhydrides such as, for example, acetic propionic anhydride, acetic butyric anhydride and the like can also be used for this purpose in some embodiments.

In most cases, the cellulose is exhaustively acetylated with the acetylating agent to produce a derivatized cellulose having a high degree of substitution (DS) value, such as from 2.4 to 3, along with some additional hydroxyl group substitution (e.g., sulfate esters) in some cases. Exhaustively acetylating the cellulose refers to an acetylation reaction that is driven toward completion such that as many hydroxyl groups as possible in cellulose undergo an acetylation reaction.

Suitable acidic catalysts for promoting the acetylation of cellulose often contain sulfuric acid or a mixture of sulfuric acid and at least one other acid. Other acidic catalysts not containing sulfuric acid can similarly be used to promote the acetylation reaction. In the case of sulfuric acid, at least some of the hydroxyl groups in the cellulose can become initially functionalized as sulfate esters during the acetylation reaction. Once exhaustively acetylated, the cellulose is then subjected to a controlled partial de-esterification step, generally in the presence of a de-esterification agent, also referred to as a controlled partial hydrolysis step.

De-esterification, as used herein, refers to a chemical reaction during which one or more of the ester groups of the intermediate cellulosic ester are cleaved from the cellulose acetate and replaced with a hydroxyl group, resulting in a cellulose acetate product having a (second) DS of less than 3. “De-esterifying agent,” as used herein, refers to a chemical agent capable of reacting with one or more of the ester groups of the cellulose acetate to form hydroxyl groups on the intermediate cellulosic ester. Suitable de-esterifying agents include low molecular weight alcohols, such as methanol, ethanol, isopropyl alcohol, pentanol, R—OH, wherein R is Cl to C20 alkyl group, and mixtures thereof. Water and a mixture of water and methanol may also be used as the de-esterifying agent. Typically, most of these sulfate esters are cleaved during the controlled partial hydrolysis used to reduce the amount of acetyl substitution. The reduced degree of substitution may range from 0.5 to 3.0, e.g., from 1.3 to 3, from 1.3 to 2.9, from 1.5 to 2.9 or from 2 to 2.6. For purposes of this disclosure, the degree of substitution is typically from 1.3 to 2.9 since below 1.3, natural degradation may occur. The degree of substitution may be selected based on the at least one organic solvent to be used in the binder composition. For example, when acetone is used as the organic solvent, the degree of substitution may range from 2.2 to 2.65. As used herein, “degradation” may refer to any degradation mechanism and rate, including photo chemical degradation, biodegradation, or any form of degradation. When comparing degradation of cellulose acetate to the filler, the comparison may be based on the same degradation mechanism so as to compare like rates.

The number average molecular weight of the cellulose ester may range from 30,000 amu to 100,000 amu, e.g., from 50,000 amu to 80,000 amu and may have a polydispersity from 1.5 to 2.5, e.g., from 1.75 to 2.25 or from 1.8 to 2.2. All molecular weight recited herein, unless otherwise specified, are number average molecular weights. The molecular weight may be selected based on the desired hardness of the final tow or filter rod. Although greater molecular weight leads to increased hardness, greater molecular weight also increases viscosity. The cellulose ester may be provided in powder or flake form.

In some aspects, blends of different molecular weight cellulose ester flake or powder may be used. Accordingly, a blend of high molecular weight cellulose ester, e.g., a cellulose ester having a molecular weight above 60,000 amu, may be blended with a low molecular weight cellulose ester, e.g., a cellulose ester having a molecular weight below 60,000 amu. The ratio of high molecular weight cellulose ester to low molecular weight cellulose ester may vary but may generally range from 1:10 to 10:1; e.g., from 1:5 to 5:1 or from 1:3 to 3:1. Blends of different cellulose esters may also be used and may include two, three, four, or more different cellulose esters in varied ratios. In some aspects, one cellulose ester may be present in a majority while other cellulose esters are present in smaller amounts.

Cellulose Ester Fibers, Tow, and Tow Bales

There are a number of methods of forming fibers from cellulose esters (e.g., cellulose acetate) which may be employed to form the tow of the present disclosure. In some embodiments, to form fibers from cellulose ester, a dope is formed by dissolving the cellulose ester flake or powder in a solvent to form a dope solution. The dope solution is typically a highly viscous solution. The solvent of the dope solution may be selected from the group consisting of water, acetone, methylethyl ketone, methylene chloride, dioxane, dimethyl formamide, methanol, ethanol, glacial acetic acid, supercritical carbon dioxide, any suitable solvent capable of dissolving the aforementioned polymers, and combinations thereof. In some aspects, the solvent is acetone or a combination of acetone and up to 5 wt. % water. The dope is then filtered and deaerated prior to being spun to form fibers, referred to as solvent-spinning. The dope may be spun in a spinner comprising one or more cabinets, each cabinet comprising a spinneret. The spinneret comprises holes that affect the rate at which the solvent evaporates from the fibers.

The filler described herein may be added to the dope and is limited by having a degradation rate that is greater than that of the cellulose ester. The degradation rate of the cellulose ester is dependent on the degree of substitution as well as the environment that the cellulose ester is exposed to for degradation. Exemplary fillers include monosaccharides (e.g., glucose, sucrose, lactose, fructose, galactose, ribose, xylose, etc.), polysaccharides (e.g., polysaccharide ester, hydrolyzed polysaccharide, oligosaccharide, starches, cellulose, including alpha-cellulose, hemicellulose, hyaluronic, alginate, guar gums, chitin, and chondroitin, modified starches, hydrolyzed starches, hemp seed polysaccharide, etc.) As described herein, the filler may be selected so that it may be included in the dope, i.e., has a small enough domain that it will not be filtered out. This size may be dependent on the size of the spinneret holes. Exemplary fillers to be included in the dope include monosaccharides, polysaccharides, polysaccharide ester, hydrolyzed polysaccharide, oligosaccharide, or combinations thereof.

The solvent may be included in the dope in an amount from 60 to 90% by weight, e.g., from 60 to 85% by weight, from 60 to 80% by weight, from 60 to 75% by weight, from 60 to 70% by weight, from 60 to 65% by weight, from 65 to 90% by weight, from 70 to 90% by weight, from 75 to 90% by weight, from 80 to 90% by weight, or from 85 to 90% by weight. All values in between are also contemplated and included.

The filler may be included in the dope in an amount sufficient to achieve the desired improvement in degradation rate of the tow, tow band, or cigarette filter while balancing the desired properties of the tow, tow band, or cigarette filter. For example, the filler may be present from 0.1 to 39% by weight of the dope, e.g., from 0.1 to 35% by weight, from 0.1 to 30% by weight, from 0.1 to 25% by weight, from 0.1 to 20% by weight by weight, from 0.1 to 15% by weight, from 0.1 to 10% by weight, from 0.1 to 7.5% by weight, or from 0.1 to 5% by weight. In further aspects, the lower limit of the filler may be at least 0.5% by weight, at least 0.75% by weight, at least 1% by weight, at least 2% by weight, or at least 3% by weight. All other values and ranges in between the above cited values are also included and contemplated.

The cellulose acetate may be included in the dope in an amount sufficient to retain the desired properties of the tow, tow band, or cigarette filter, e.g., filtration of the cigarette filter. For example, the cellulose acetate may be present from 0.1 to 39.9% by weight of the dope, e.g., from 0.1 to 37.5% by weight, from 0.1 to 35% by weight, from 0.1 to 30% by weight, from 0.1 to 25% by weight by weight, from 0.1 to 20% by weight, from 0.1 to 15% by weight, from 0.1 to 10% by weight, from 0.1 to 7.5% by weight, or from 0.1 to 5% by weight. In further aspects, the lower limit of the cellulose acetate may be at least 0.5% by weight, at least 0.75% by weight, at least 1% by weight, at least 2% by weight, at least 3% by weight, at least 5% by weight, at least 10% by weight, at least 15% by weight, at least 20% by weight, at least 25% by weight, at least 30% by weight, at least 35% by weight, at least 37.5%, at least 39%, or at least 39.5%. All other values and ranges in between the above cited values are also included and contemplated.

Pigments may also be added to the dope. The dope may comprise, for example, from 5 to 40 wt. % cellulose acetate, from 0.1 to 35% filler, and from 60 to 90 wt. % solvent. Pigments, when added, may be present from 0.1 to 5 wt. %, e.g., from 0.1 to 4 wt. %, from 0.1 to 3 wt. % from 0.1 to 2 wt. %, from 0.5 to 5 wt. %, from 0.5 to 4 wt. %, from 0.5 to 3 wt. %, from 0.5 to 2 wt. %, from 1 to 5 wt. %, from 1 to 4 wt. %, from 1 to 3 wt. % or from 1 to 2 wt. %. The pigment added to the dope is not particularly limited, and any conventional pigment may be used. Examples of common, suitable pigments include calcium carbonate, diatomaceous earth, magnesium oxide, zinc oxide, and barium sulfate.

Generally, the production of a bale of tow bands may involve spinning fibers from the dope, forming a tow containing the fibers, forming a tow band from the fibers, crimping the tow band, and baling the crimped tow band. Within said production, optional steps may include, but are not limited to, warming the fibers after spinning, applying a finish or additive to the fibers and/or tow band prior to crimping, and conditioning the crimped tow band. The parameters of at least these steps are important for producing desirable bales.

In some aspects, if the filler has too large of a domain to be included in the dope, the filler may be included at a later point in the process, such as any of the steps described above. Specifically, the filler may be added to the cellulose acetate flake.

It should be noted that bales may vary in size and shape as needed for further processing. In some embodiments, bales may have dimensions ranging from 30 inches (76 cm) to 60 inches (152 cm) in height, 46 inches (117 cm) to 56 inches (142 cm) in length, and 35 inches (89 cm) to 45 inches (114 cm) in width. In some embodiments, bales may range in weight from 900 pounds (408 kg) to 2100 pounds (953 kg). In some embodiments, bales may have a density greater than 300 kg/m3 (18.8 lb/ft3).

Fibers

The structure of the cellulose acetate fibers for use in the present disclosure is not particularly limited, and various known fiber structures may be employed. For example, the tow band may utilize fibers having a broad range of denier per filament (dpf). In some embodiments, the tow band has from 1 to 30 dpf, e.g., from 2 to 28 dpf, from 3 to 25 dpf, from 4 to 22 dpf, from 5 to 30 dpf, from 5 to 28 dpf, from 5 to 25 dpf, from 5 to 22 dpf, from 10 to 30 dpf, from 10 to 28 dpf, from 10 to 25 dpf, from 10 to 22 dpf, from 15 to 30 dpf, from 15 to 28 dpf, from 15 to 25 dpf, from 15 to 22 dpf, from 20 to 30 dpf, from 20 to 28 dpf, from 20 to 25 dpf, or from 20 to 22 dpf.

The fibers for use in the present disclosure may have any suitable cross-sectional shape, including, but not limited to, circular, substantially circular, crenulated, ovular, substantially ovular, polygonal, substantially polygonal, dog-bone, “Y,” “X,” “K,” “C,” multi-lobe, and any hybrid thereof. As used herein, the term “multi-lobe” refers to a cross-sectional shape having a point (not necessarily in the center of the cross-section) from which at least two lobes extend (not necessarily evenly spaced or evenly sized).

As noted above, fibers for use in the present disclosure may be produced by any method known to one skilled in the art. As noted, in some embodiments, fibers may be produced by spinning a dope through a spinneret. As used herein, the term “dope” refers to a cellulose acetate solution and/or suspension from which fibers are produced. In some embodiments, a dope may comprise cellulose acetate, filler, and solvents. In some embodiments, a dope for use in conjunction with the present disclosure may comprise cellulose acetate, filler, solvents, and additives. In some embodiments, the cellulose acetate may be at a concentration in the dope ranging from 10 to 40 wt. percent (e.g., from 20 to 30 wt. %, from 25 to 40 wt. %, from 25 to 30 wt. %), and the solvent may be at a concentration from 60 to 90 wt. % (e.g., 60 to 80 wt. %, 70 to 80 wt. %, 80 to 90 wt. %). The filler and additives may make up the remainder of the dope. In some embodiments, the dope may be heated to a temperature ranging from 40° C. to 100° C. (e.g., from 45° C. to 95° C., from 50° C. to 90° C., from 55° C. to 85° C., from 60° C. to 80° C.).

Suitable solvents may include, but not be limited to, water, acetone, methylethyl ketone, methylene chloride, dioxane, dimethyl formamide, methanol, ethanol, glacial acetic acid, supercritical CO2, any suitable solvent capable of dissolving the aforementioned polymers, or any combination thereof. By way of nonlimiting example, a solvent for cellulose acetate may be an acetone/methanol mixture. In some embodiments, to produce very high dpf values of the present disclosure, increased solvent levels compared with amounts for typical dpf values (e.g., 2 to 8 dpf) may be used. For example in some embodiments, to produce very high dpf tow, solvent amounts may be from 5 to 30 wt. % greater when compared with solvent amounts for typical dpf tow. Additional solvent amounts may, in some cases, present challenges to the processing of the fibers.

Some embodiments of the present disclosure may involve treating fibers to achieve surface functionality on the fibers. In some embodiments, fibers may comprise a surface functionality including, but not limited to, biodegradability sites (e.g., defect sites to increase surface area to enhance biodegradability), chemical handles (e.g., carboxylic acid groups for subsequent functionalization), active particle binding sites (e.g., sulfide sites binding gold particles or chelating groups for binding iron oxide particles), sulfur moieties, or any combination thereof. One skilled in the art should understand the plurality of methods and mechanisms to achieve surface functionalities. Some embodiments may involve dipping, spraying, ionizing, functionalizing, acidizing, hydrolyzing, exposing to a plasma, exposing to an ionized gas, or any combination thereof to achieve surface functionalities. Suitable chemicals to impart a surface functionality may be any chemical or collection of chemicals capable of reacting with cellulose acetate including, but not limited to, acids (e.g., sulfuric acid, nitric acid, acetic acid, hydrofluoric acid, hydrochloric acid, and the like), reducing agents (e.g., LiAlH4, NaBH4, H2/Pt, and the like), Grignard reagents (e.g., CH3MgBr, and the like), trans-esterification reagent, amines (e.g., R—NH3 like CH3NH3), or any combination thereof. Exposure to plasmas and/or ionized gases may react with the surface, produce defects in the surface, or any combination thereof. Said defects may increase the surface area of the fibers which may yield higher loading and/or higher filtration efficacy in the final filter products.

Some embodiments of the present disclosure may involve applying a finish to the fibers. Suitable finishes may include, but not be limited to, at least one of the following: oils (e.g., mineral oils or liquid petroleum derivatives), water, additives, or any combination thereof. Examples of suitable mineral oils may include, but not be limited to, water white (i.e., clear) mineral oil having a viscosity of 80-95 SUS (Sabolt Universal Seconds) measured at 38° C. (100° F.). Examples of suitable emulsifiers may include, but not be limited to, sorbitan monolaurate, e.g., SPAN® 20 (available from Croda, Wilmington, Del.), poly(ethylene oxide) sorbitan monolaurate, e.g., TWEEN® 20 (available from Croda, Wilmington, Del.). The water may be de-mineralized water, de-ionized water, or otherwise appropriately filtered and treated water. The lubricant or finish may be applied by spraying or wiping. Generally, the lubricant or finish is added to the fiber prior to forming the fibers into tow.

In some embodiments of the present disclosure, finish may be applied as a neat finish or as a finish emulsion in water. As used herein, the term “neat finish” refers to a finish formulation without the addition of excess water. It should be noted that finish formulations may comprise water. In some embodiments, finish may be applied neat followed by applying water separately.

In some embodiments of the present disclosure, a finished emulsion may comprise less than 98% water, less than 95%, less than 92%, or less than 85%. In some embodiments, it may be advantageous in later steps to have fibers having a lower weight percentage of moisture (e.g., 5% to 25% w/w of the tow band), of which water is a contributor. The water content of the finished emulsion may be at least one parameter that may assist in achieving said weight percentage of moisture in the fibers. Therefore, in some embodiments, a finished emulsion may comprise less than 92% water, less than 85% water, or less than 75% water.

Tow

Once the dope is formed and solvent-spun, the solvent is evaporated and the dope is spun and extruded to form a plurality of extruded fibers, referred to as tow.

The filler may be included in the tow in an amount sufficient to achieve the desired improvement in degradation rate of the tow, tow band, or cigarette filter while balancing the desired properties of the tow, tow band, or cigarette filter. For example, the filler may be present from 0.1 to 99% by weight of the tow, e.g., from 0.1 to 95% by weight, from 0.1 to 90% by weight, from 0.1 to 85% by weight, from 0.1 to 80% by weight by weight, from 0.1 to 75% by weight, from 0.1 to 70% by weight, from 0.1 to 65% by weight, from 0.1 to 60% by weight, from 0.1 to 55% by weight, from 0.1 to 50% by weight, from 0.1 to 45% by weight, from 0.1 to 40% by weight, from 0.1 to 35% by weight, from 0.1 to 30% by weight, from 0.1 to 25% by weight, from 0.1 to 20% by weight, from 0.1 to 15% by weight, from 0.1 to 10% by weight, or from 0.1 to 5% by weight. In further aspects, the lower limit of the filler may be at least 0.5% by weight, at least 0.75% by weight, at least 1% by weight, at least 2% by weight, or at least 3% by weight. All other values and ranges in between the above cited values are also included and contemplated.

The cellulose acetate may be included in the tow in an amount sufficient to retain the desired properties of the tow, tow band, or cigarette filter, e.g., filtration of the cigarette filter. For example, the cellulose acetate may be present from 0.1 to 99% by weight of the tow, e.g., from 0.1 to 95% by weight, from 0.1 to 90% by weight, from 0.1 to 85% by weight, from 0.1 to 80% by weight by weight, from 0.1 to 75% by weight, from 0.1 to 70% by weight, from 0.1 to 65% by weight, from 0.1 to 60% by weight, from 0.1 to 55% by weight, from 0.1 to 50% by weight, from 0.1 to 45% by weight, from 0.1 to 40% by weight, from 0.1 to 35% by weight, from 0.1 to 30% by weight, from 0.1 to 25% by weight, from 0.1 to 20% by weight, from 0.1 to 15% by weight, from 0.1 to 10% by weight, or from 0.1 to 5% by weight. In further aspects, the lower limit of the cellulose acetate may be at least 0.5% by weight, at least 0.75% by weight, at least 1% by weight, at least 2% by weight, at least 3% by weight, at least 5% by weight, at least 10% by weight, at least 15% by weight, at least 20% by weight, at least 25% by weight, at least 30% by weight, at least 35% by weight, at least 40% by weight, at least 45% by weight, at least 50% by weight, or greater. All other values and ranges in between the above cited values are also included and contemplated. Furthermore, the above included ranges for the tow also apply to the tow band and filter rod incorporated into a cigarette filter.

The weight ratio of the cellulose acetate to the filler in the dope, tow, tow band, filter rod, and cigarette filter may also vary, including from 1:99 to 99:1, e.g., from 1:75 to 75:1, from 1:50 to 50:1, from 1:25 to 25:1, from 1:10 to 10:1, from 1:5 to 5:1, from 1:3 to 3:1, from 1:2 to 2:1, or approximately 1:1. In some embodiments, the cellulose acetate is present in a greater weight ratio than the filler, e.g., at least 1.5:1, at least 2:1, at least 3:1, at least 5:1, at least 10:1, at least 15:1, at least 20:1, at least 25:5, or at least 50:1, including all ranges in between.

The tow, tow band, filter rod, and cigarette filter may also comprise additives. The additives may be present in an amount from 0.01 to 25% by weight, e.g., from 0.01 to 20% by weight, from 0.1 to 20% by weight, from 0.1 to 15% by weight, from 0.1 to 10% by weight, or from 0.1 to 5% by weight. In further aspects, the lower limit of the cellulose acetate may be at least 0.5% by weight, at least 0.75% by weight, at least 1% by weight, at least 2% by weight, at least 3% by weight, at least 5% by weight, at least 10% by weight, at least 15% by weight, at least 20% by weight, at least 25% by weight, at least 30% by weight, at least 35% by weight, at least 40% by weight, at least 45% by weight, at least 50% by weight, or greater. All other values and ranges in between the above cited values are also included and contemplated.

Once the tow is formed, it may be combined to form a tow band which comprises a plurality of tow filaments. In some embodiments, the tow band is from 10,000 to 100,000 total denier, e.g., from 15,000 to 100,000, from 20,000 to 100,000, from 25,000 to 100,000, from 30,000 to 100,000, from 10,000 to 90,000, from 15,000 to 90,000, from 20,000 to 90,000, from 25,000 to 90,000, from 30,000 to 90,000, from 10,000 to 90,000, from 15,000 to 90,000, from 20,000 to 90,000, from 25,000 to 90,000, from 30,000 to 90,000, from 10,000 to 80,000, from 15,000 to 80,000, from 20,000 to 80,000, from 25,000 to 80,000, from 30,000 to 80,000, from 10,000 to 70,000, from 15,000 to 70,000, from 20,000 to 70,000, from 25,000 to 70,000, from 30,000 to 70,000, from 10,000 to 60,000, from 15,000 to 60,000, from 20,000 to 60,000, from 25,000 to 60,000, or from 30,000 to 60,000. In terms of upper limits, the tow band may be less than 100,000 total denier, e.g., less than 90,000, less than 80,000, less than 70,000, or less than 60,000. In terms of lower limits, the tow band may be greater than 10,000 total denier, e.g., greater than 15,000, greater than 20,000, greater than 25,000, or greater than 30,000.

In some embodiments, the tow can have a breaking strength between 3.5 kg and 25 kg, e.g. from 3.5 kg to 22.5 kg, from 3.5 kg to 20 kg, from 3.5 kg to 17.5 kg, from 3.5 kg to 15 kg, from 4 kg to 25 kg, from 4 kg to 22.5 kg, from 4 kg to 20 kg, from 4 kg to 17.5 kg, from 4 kg to 15 kg, from 4.5 kg to 25 kg, from 4.5 kg to 22.5 kg, from 4.5 kg to 20 kg, from 4.5 kg to 17.5 kg, from 4.5 kg to 15 kg, from 5 kg to 25 kg, from 5 kg to 22.5 kg, from 5 kg to 20 kg, from 5 kg to 17.5 kg, or from 5 kg to 15 kg. In terms of upper limits, the tow may have a breaking strength of less than 25 kg, e.g., less than 22.5 kg, less than 20 kg, less than 17.5 kg, or less than 15 kg. In terms of lower limits, the tow may have a breaking strength of greater than 3.5 kg, e.g. greater than 4 kg, greater than 4.5 kg, or greater than 5 kg.

In some embodiments of the present disclosure, a tow band may comprise more than one type of fiber. In some embodiments, the more than one type of fiber may vary based on dpf, cross-sectional shape, composition, treatment prior to forming the tow band, or any combination thereof. Examples of suitable additional fibers may include, but are not limited to, carbon fibers, activated carbon fibers, natural fibers, synthetic fibers, or any combination thereof. Further examples include some cellulose acetate tow that includes filler and some cellulose acetate tow that does not include filler. The weight ratio of tow including filler to tow excluding filler may range from 1:99 to 99:1, e.g., from 1:75 to 75:1, from 1:50 to 50:1, from 1:25 to 25:1, from 1:10 to 10:1, from 1:5 to 5:1, from 1:3 to 3:1, from 1:2 to 2:1, or approximately 1:1. In some embodiments, the cellulose acetate is present in a greater weight ratio than the filler, e.g., at least 1.5:1, at least 2:1, at least 3:1, at least 5:1, at least 10:1, at least 15:1, at least 20:1, at least 25:5, or at least 50:1, including all ranges in between. It is also contemplated that different types of filler may be included in different tow, which is ultimately combined to form a tow band. For example, some tow filaments may include a monosaccharide while other tow filaments may include a different filler, such as a polysaccharide or a starch. Additionally, the tow may include filler that is integral to the tow, e.g., added to the flake, powder, or dope, and filler that is added at a later part of the manufacturing process, such as a cellulose or certain starches.

Some embodiments of the present disclosure may include crimping the tow band to form a crimped tow band. Crimping the tow band may involve using any suitable crimping technique known to those skilled in the art. These techniques may include a variety of apparatuses including, but not limited to, a stuffer box or a gear. Nonlimiting examples of crimping apparatuses and the mechanisms by which they work can be found in U.S. Pat. Nos. 7,610,852 and 7,585,441, the entire contents and disclosures of which are incorporated herein by reference. Suitable stuffer box crimpers may have smooth crimper nip rolls, threaded or grooved crimper nip rolls, textured crimper nip rolls, upper flaps, lower flaps, or any combination thereof

The configuration of the crimp may play a role in the processability of the final bale. Examples of crimp configurations may include, but not be limited to, lateral, vertical, some degree between lateral and vertical, random, or any combination thereof. As used herein, the term “lateral” when describing crimp orientation refers to crimp or fiber bends in the plane of the tow band. As used herein, the term “vertical” when describing a crimp orientation refers to crimp projecting outside of the plane of the tow band and perpendicular to the plane of the tow band. It should be noted that the terms lateral and vertical refer to general overall crimp orientation and may have deviation from said configuration by +/−30 degrees.

In some embodiments of the present disclosure, a crimped tow band may comprise fibers with a first crimp configuration and fibers with a second crimp configuration.

In some embodiments of the present disclosure, a crimped tow band may comprise fibers with at least a vertical crimp configuration near the edges and fibers with at least a lateral crimp configuration near the center. In some embodiments, a crimped tow band may comprise fibers with a vertical crimp configuration near the edges and fibers with a lateral crimp configuration near the center.

The configuration of the crimp may be important for the processability of the final bale in subsequent processing steps, e.g., a lateral crimp configuration may provide better cohesion of fibers than a vertical crimp configuration unless further steps are taken to enhance cohesion. Methods for crimping tow bands with a substantially later crimp configuration are disclosed, for example, in U.S. Pub. No. 2013/0115452 and U.S. Pub. No. 2015/0128964, each of which is incorporated herein in its entirety.

In some embodiments of the present disclosure, the fibers may be adhered to each other to provide better processability of the final bale. While adhesion additives may be used in conjunction with any crimp configuration, it may be advantageous to use adhesion additives with a vertical crimp configuration. In some embodiments, adhering may involve adhesion additives on and/or in the fibers. Examples of such adhesion additives may include, but not be limited to, binders, adhesives, resins, tackifiers, or any combination thereof. It should be noted that any additive described herein, or otherwise, capable of adhering two fibers together may be used, which may include, but not be limited to, active particles, active compounds, ionic resins, zeolites, nanoparticles, ceramic particles, softening agents, plasticizers, pigments, dyes, flavorants, aromas, controlled release vesicles, surface modification agents, lubricating agents, emulsifiers, vitamins, peroxides, biocides, antifungals, antimicrobials, antistatic agents, flame retardants, antifoaming agents, degradation agents, conductivity modifying agents, stabilizing agents, or any combination thereof. Some embodiments of the present disclosure may involve adding adhesive additives to the fibers (in, on, or both) by incorporating the adhesive additives into the dope, incorporating the adhesive additives into the finish, applying the adhesive additives to the fibers (before, after, and/or during forming the tow band), applying the adhesive additives to the tow band (before, after, and/or during crimping), or any combination thereof.

Adhesive additives may be included in and/or on the fibers at a concentration sufficient to adhere the fibers together at a plurality of contact points to provide better processability of the final bale. The concentration of adhesive additives to use may depend on the type of adhesive additive and the strength of adhesion the adhesive additive provides. In some embodiments, the concentration of adhesive additive may range from a lower limit of 0.01%, 0.05%, 0.1%, or 0.25% to an upper limit of 5%, 2.5%, 1%, or 0.5% by weight of the tow band in the final bale. It should be noted that for additives that are used for more than adhesion, the concentration in the tow band in the final bale may be higher, e.g., 25% or less.

Further, some embodiments of the present disclosure may involve heating the fibers before, after, and/or during crimping. While said heating may be used in conjunction with any crimp configuration, it may be advantageous to use said heating with a vertical crimp configuration. Said heating may involve exposing the fibers of the tow band to steam, aerosolized compounds (e.g., plasticizers), liquids, heated fluids, direct heat sources, indirect heat sources, irradiation sources that causes additives in the fibers (e.g., nanoparticles) to produce heat, or any combination thereof.

Some embodiments of the present disclosure may include conditioning the crimped tow band. Conditioning may be used to achieve a crimped tow band having a residual acetone content of 0.5% or less w/w of the crimped tow band. Conditioning may be used to achieve a crimped tow band having a residual water content of 8% or less w/w of the crimped tow band. Conditioning may involve exposing the fibers of the crimped tow band to steam, aerosolized compounds (e.g., plasticizers), liquids, heated fluids, direct heat sources, indirect heat sources, irradiation sources that causes additives in the fibers (e.g., nanoparticles) to produce heat, or any combination thereof.

UCE is the amount of work required to uncrimp a fiber. UCE, as reported hereinafter, is sampled prior to baling, i.e., post-drying and pre-baling. UCE, as used herein, is measured as follows: using a warmed up (20 minutes before conventional calibration) Instron tensile tester (Model 1130, crosshead gears—Gear #'s R1940-1 and R940-2, Instron Series IX-Version 6 data acquisition & analysis software, Instron 50 Kg maximum capacity load cell, Instron top roller assembly, 1″×4″×⅛″ thick high grade Buna-N 70 Shore A durometer rubber grip faces), a preconditioned tow sample (preconditioned for 24 hours at 22° C. ±2° C. and Relative humidity at 60%±2%) of about 76 cm in length is looped over and spread evenly across the center of the top roller, pre-tensioned by gently pulling to 100 g±2 g (per readout display), and each end of the sample is clamped (at the highest available pressure, but not exceeding the manufacturers recommendations) in the lower grips to effect a 50 cm gauge length (gauge length measured from top of the robber grips), and then tested, until break, at a crosshead speed of 30 cm/minute. This test is repeated until three acceptable tests are obtained and the average of the three data points from these tests is reported. Energy (E) limits are between 0.220 kg and 10.0 kg. Displacement (D) has a preset point of 10.0 kg. UCE is calculated by the formula: UCE (gcm/cm)=(E*1000)/((D*2)+500). Breaking strength can be calculated using the same test and the following equation BS=L (where L is the load at max load (kg)). In certain embodiments of the disclosure, UCE values (in gcm/cm) can range from 190 to 400, e.g., 200 to 300, e.g., 290. In certain embodiments of the disclosure breaking strength can range from between 3.5 kg and 25 kg, e.g. 4 kg to 20 kg, 4.5 kg to 15 kg, or 5 kg to 12 kg.

Cigarette Filter

A degradable cigarette filter generally includes a filter element (or filter plug) made of a bloomed cellulose acetate tow comprising the filler and a plug wrap surrounding the filter element. Cellulose acetate tow may be delivered to a filter producer as a bale. The tow is then opened or “bloomed” in rodmaking equipment in order to form the filter rod and eventual cigarette filter. Various properties are desirable for a cigarette filter, including firmness, pressure drop, pressure drop variability, openability, fly, and uncramping energy. The filler described herein, as well as the amount used, may be chosen to balance these properties with degradability of the cigarette filter.

EMBODIMENTS

Embodiment 1: A cellulose acetate tow band, the tow band comprising: a) cellulose acetate having a degree of substitution (DS) of greater than 1.3; and b) a filler; wherein the filler has a greater rate of degradation than the cellulose acetate.

Embodiment 2: The tow band according to Embodiment 1, wherein the filler comprises a monosaccharide, polysaccharide, polysaccharide ester, hydrolyzed polysaccharide, oligosaccharide, or combinations thereof

Embodiment 3: The tow band according to Embodiment 1 or 2, wherein the filler comprises dextran, a hydrolyzed starch, a modified hydrolyzed starch, hemp, cellulose, or combinations thereof

Embodiment 4: The tow band according to any of Embodiments 1-3, wherein the filler is present from 0.1 to 99.9% by weight, based on the total weight of the tow band.

Embodiment 5: The tow band according to any of Embodiments 1-4, wherein the filler is present from 0.1 to 75% by weight, based on the total weight of the tow band.

Embodiment 6: The tow band according to any of Embodiments 1-5, wherein the filler is present from 0.1 to 50% by weight, based on the total weight of the tow band.

Embodiment 7: The tow band according to any of Embodiments 1-6, wherein the filler is present from 0.1 to 25% by weight, based on the total weight of the tow band.

Embodiment 8: The tow band according to any of Embodiments 1-7, wherein the degradation rate of the filler is at least 3% greater than that of the cellulose acetate.

Embodiment 9: The tow band according to any of Embodiments 1-8, wherein the degradation rate of the filler is at least 10% greater than that of the cellulose acetate.

Embodiment 10: The tow band according to any of Embodiments 1-9, wherein the degradation rate of the filler is at least 15% greater than that of the cellulose acetate.

Embodiment 11: The tow band according to any of Embodiments 1-10, wherein the tow band comprises a weight ratio of the cellulose acetate to the filler from 1:99 to 99:1.

Embodiment 12: The tow band according to any of Embodiments 1-11, wherein the tow band comprises a weight ratio of the cellulose acetate to the filler from 1:50 to 50:1.

Embodiment 13: The tow band according to any of Embodiments 1-12, wherein the tow band comprises a weight ratio of the cellulose acetate to the filler from 1:25 to 25:1.

Embodiment 14: The tow band according to any of Embodiments 1-13, wherein the tow band comprises cellulose acetate is an amount from 0.1 to 99.9% by weight, based on the total weight of the tow band.

Embodiment 15: The tow band according to any of Embodiments 1-14, wherein the cellulose acetate has a degree of substitution from 1.3 to 2.9 or from 2 to 2.9.

Embodiment 16: The tow band according to any of Embodiments 1-15, wherein the tow band comprises from 0.01 to 25% by weight additives, based on the total weight of the tow band.

Embodiment 17: A cigarette filter comprising: a filter element comprising bloomed tow, wherein the bloomed tow comprises the tow band according to any of Embodiments 1-16.

Embodiment 18: A method for forming the cigarette filter of Embodiment 17, the method comprising a) providing the cellulose acetate tow band; b) blooming the tow band; and c) forming the bloomed tow band into a filter rod.

Embodiment 19: The method of Embodiment 18, wherein the tow band is formed by: a) combining cellulose acetate and the filler with a solvent to form a dope; b) solvent-spinning the dope to form a plurality of tow filaments; and c) combining the plurality of tow filaments to form the tow band.

Embodiment 20: The method of Embodiment 18, wherein the tow band is formed by: a) combining cellulose acetate and the filler to form a flake; b) combining the flake with a solvent to form a dope; c) solvent-spinning the dope to form a plurality of tow filaments; and d) combining the plurality of tow filaments to form the tow band.

While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. It should be understood that aspects of the invention and portions of various embodiments and various features recited above and/or in the appended claims may be combined or interchanged either in whole or in part. In the foregoing descriptions of the various embodiments, those embodiments which refer to another embodiment may be appropriately combined with other embodiments as will be appreciated by one of ordinary skill in the art. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention. 

We claim:
 1. A cellulose acetate tow band, the tow band comprising: a) cellulose acetate having a degree of substitution (DS) of greater than 1.3; and b) a filler; wherein the filler has a greater rate of degradation than the cellulose acetate.
 2. The tow band according to claim 1, wherein the filler comprises a monosaccharide, polysaccharide, polysaccharide ester, hydrolyzed polysaccharide, oligosaccharide, or combinations thereof
 3. The tow band according to claim 1, wherein the filler comprises dextran, a hydrolyzed starch, a modified hydrolyzed starch, hemp, cellulose, or combinations thereof.
 4. The tow band according to claim 1, wherein the filler is present from 0.1 to 99.9% by weight, based on the total weight of the tow band.
 5. The tow band according to claim 1, wherein the filler is present from 0.1 to 75% by weight, based on the total weight of the tow band.
 6. The tow band according to claim 1, wherein the filler is present from 0.1 to 50% by weight, based on the total weight of the tow band.
 7. The tow band according to claim 1, wherein the filler is present from 0.1 to 25% by weight, based on the total weight of the tow band.
 8. The tow band according to claim 1, wherein the degradation rate of the filler is at least 3% greater than that of the cellulose acetate.
 9. The tow band according to claim 1, wherein the degradation rate of the filler is at least 10% greater than that of the cellulose acetate.
 10. The tow band according to claim 1, wherein the degradation rate of the filler is at least 15% greater than that of the cellulose acetate.
 11. The tow band according to claim 1, wherein the tow band comprises a weight ratio of the cellulose acetate to the filler from 1:99 to 99:1.
 12. The tow band according to claim 1, wherein the tow band comprises a weight ratio of the cellulose acetate to the filler from 1:50 to 50:1.
 13. The tow band according to claim 1, wherein the tow band comprises a weight ratio of the cellulose acetate to the filler from 1:25 to 25:1.
 14. The tow band according to claim 1, wherein the tow band comprises cellulose acetate in an amount from 0.1 to 99.9% by weight, based on the total weight of the tow band.
 15. The tow band according to claim 1, wherein the cellulose acetate has a degree of substitution from 2 to 2.9.
 16. The tow band according to claim 1, wherein the tow band comprises from 0.01 to 25% by weight additives, based on the total weight of the tow band.
 17. A cigarette filter comprising: a filter element comprising bloomed tow, wherein the bloomed tow comprises the tow band according to claim
 1. 18. A method for forming the cigarette filter of claim 17, the method comprising a) providing the cellulose acetate tow band; b) blooming the tow band; and c) forming the bloomed tow band into a filter rod.
 19. The method of claim 18, wherein the tow band is formed by: a) combining cellulose acetate and the filler with a solvent to form a dope; b) solvent-spinning the dope to form a plurality of tow filaments; and c) combining the plurality of tow filaments to form the tow band.
 20. The method of claim 18, wherein the tow band is formed by: a) combining cellulose acetate and the filler to form a flake; b) combining the flake with a solvent to form a dope; c) solvent-spinning the dope to form a plurality of tow filaments; and d) combining the plurality of tow filaments to form the tow band. 